On Nondeterministic Workflow Executions

Abstract

The ability to compose existing services to form new functionality is one of the most promising ideas enabled by SOA and the framework of (web) services. A composition or a workflow often involves services distributed over a network and possibly many organizations and administrative domains. Nondeterminism could occur in a composition in at least two ways. The first form is the result of modeling abstraction that hides the detail information and thus makes the “computation” appear non-deterministic. The second form is closely related to “operational optimization”, e.g., one may try to invoke more than multiple services for a task, whichever completes first will produce the result and preempts all other services. In this paper, we focus on the latter and measure the complexity of service execution as the amount of needed resources and controlling mechanism for executing nondeterministic service compositions. We formalize the model and complexity problem and develop technical results for this problem in the general setting as well as special cases.

Keywords

State Machine Service Composition Terminal Node Regular Language Topological Order

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